1. Field of the Invention
The present invention relates to a composite thin film magnetic head capable of magnetic process of both reading and writing to a magnetic recording medium, and head gimbal assembly, head arm assembly and magnetic disk device, all equipped with the composite thin film magnetic head.
2. Description of the Related Art
In recent years, with the improvement of a real recording density of a magnetic recording medium (hereinafter, simply referred to as a recording medium) such as a hard disk or the like, the performance improvement of the thin film magnetic head mounted on the magnetic recording device such as hard disk drives is desirable.
As the recording method of the thin film magnetic head, for example, there is known a perpendicular recording method to set the direction of the signal magnetic field to the direction orthogonal to the recording medium surface. In the recording head of the perpendicular recording method, for example, the following is provided: a thin film coil generating the magnetic flux for recording, and a main magnetic pole layer extending backward from the recording-medium-facing surface (hereinafter, simply referred to as an “air bearing surface”) and conducting the magnetic flux to the recording medium so that the magnetic medium is magnetized in the direction orthogonal to the recording medium surface. In the recording head, the magnetic medium is magnetized by the magnetic field for recording. Thus information is magnetically recorded on the recording medium.
As the recording head, for example, there is known a recording head provided with a main magnetic pole layer disposed like extending in the direction orthogonal to the air bearing surface. This type of the recording head is generally referred to as a “single pole head”. As a specific structure of the simple pole head, for example, there is known a structure that the intensity of the recording magnetic field is increased in order to improve the overwrite properties, and an auxiliary magnetic pole layer for auxiliary magnetic flux accommodation is coupled with the main magnetic pole layer.
Further, for example, recently such a recording head becomes a mainstream that provided with a main magnetic pole layer extending in the direction orthogonal to the air bearing surface as described above to increase the recording density of the recording medium by suppressing the expansion of the recording track width, and a write shield layer to suppress the spread of the magnetic flux released from the main magnetic pole layer. This type of the recording head is generally referred to as a “shield type head”. The write shield layer is formed extending backward from the air bearing surface, and the front edge thereof is disposed apart from the main magnetic pole layer with the gap layer in between. As a specific structure of the shield type head, for example, there is known a structure that the write shield layer is disposed on the trailing side of the main magnetic pole layer (Japanese Unexamined Patent Publication No. 2005-108412). In the shield type head provided with the write shield layer, the expansion of the magnetic flux released from the main magnetic pole layer is suppressed so that the gradient of the recording magnetic field is sharply increased; thereby the recording density of the recording medium is improved.
The reproducing head is provided with, for example, a shield gap film, and a pair of lead shield layers to sandwich the shield gap film. A magnetoresistive element including the magnetization free layer changing the magnetization direction according to the signal magnetic field from the magnetic recording medium is buried in the shield gap film. This type of a reproducing head also has a function as a current path that a pair of lead shield layers flow a current in the stacking direction of the magnetoresistive element. Thus the reproducing head reads the recorded information by using the change of the electric resistance of the magnetoresistive element according to the signal magnetic field from the magnetic recording medium.